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Doublereed Archive - Posting 000040.txt from 2004/01

From: "Knorr" <bknorr01@-----.com>
Subj: Re: [DR-L] Researching Plastic Reeds
Date: Fri, 9 Jan 2004 23:45:21 -0500

Since I am a material engineer (my day job), I would like to make some comm
ents on the potential for plastics in reeds. Polymer materials (the more t
echnical term for plastics) are all composed long molecules with a backbone
of primarily carbon-carbon chemical bonds. These bonds are very strong.
The chemical bonds between the long polymer molecules are much weaker. Ima
gine a plate of spagetti, where each strand represents a polymer chain. Th
e plate of spagetti consists of random, twisted strands analogous to an unp
rocessed polymer. If you were to gently comb the strands, they would gradu
ally align. In the same way, deforming a block of polymer would gradually
align the chain-like molecules. The result is properties that are very dif
ferent comparing the direction of alignment to a direction 90 degrees away.
The result would not be unlike cane, which has very different properties
along the grain versus across the grain (wood is actually a naturally occur
ring composite, but that is another story).

Polyethylene is perhaps the simplest of all polymers. It consists of only
a chain of carbon atoms and hydrogen atoms at all other sites on the chain.
Consequently, it is the easiest polymer to align. UHMWPE only means that
the chains are very long; the basic structure is still the same. Very hig
hly aligned high density polyethylene (HDPE) is available commercially unde
r the trade name SPECTRA, I believe. This stuff is very strong along the l
ength of the fiber with a specific strength (strength divided by density) s
tronger than steel. It is certainly feasible that some form of polyethylen
e could be extruded into tubes, thereby aligning it. However, very high re
duction ratios would likely be necessary. Such fabrication is quite easy i
f you have the proper equipment - it is done routinely for metals. The key
to making it work would be balancing a number of processing variables and
choosing the length of polyethylene chain (or mixture of several lengths).
This would be a fascinating engineering project (I am not volunteering).
The development time and cost have probably not been justified by the perce
ived market volume required to write down the capital and development costs
. If it were developed, my guess is that the cost with any kind of volume
would be pretty cheap based only on the starting material and processing.

Just my 2x10^-2 cents. Class dismissed.

Dave Knorr
----- Original Message -----
From: PhilFrei@-----.com
To: doublereed-l@-----.edu
Sent: Friday, January 09, 2004 3:58 PM
Subject: [DR-L] Researching Plastic Reeds

I just had a very interesting browsing session!

The Legere company (http://www.legere.com) listed its patent number. So I
went to the US Patent office website (just type US Patents in Google), and
discovered that any patent from the last 20 or 30 years is viewable online!

It seems that patents have a "Description" section and "Prior Art" sectio
n which are generally pretty readable. They also list other patents that ar
e related. In browsing through these patents I discovered people have been
very busy trying to make successful synthetic reeds.

It seems the big problem is that in order to get a man-made material to v
ibrate at a high enough frequency (necessary for high notes and overtones),
it has to be so massive that the air pressures we create with our breath a
re not strong enough to move it sufficiently. Arundo Donax is unique in its
high strength and low density.

Some of the past patents describe ideas that attempt to layer stronger ca
rbon fibre with low density filler, even air pocket layers. Others refer to
the use of stainless steel, magnesium, or even titanium reeds. I've never
seen any of these come to market, though.

However, there has recently been advances made with polyethelene. I think
the research has been driven in part by the prosthetics industry, where a
stronger plastic would allow prosthetics of less bulk. According to the bac
kground on one of the patents, polyethelene has carbon-to-carbon links, pot
entially very strong. But these connections are not organized or layed out
in a way that realizes this potential strength. Recent research has had som
e success in producing what is refered to as UHMWPE, or ultra high molecula
r weight polyethelene. There are special extrusion and cooling processes th
at I can't begin to understand or describe which somehow line up the carbon
to carbon links in a way that emphazes their strength.

Legere's patent refers to the use of such plastics in the making of reeds
. I don't know if this plastic is commercially available yet or not in a fo
rm we could use ourselves. Legere's web site claims it is not, but perhaps
it is just a matter of time, as the high-strength plastics would certainly
have a lot of commercial uses.

Another entirely different line of investigation would be to try and find
shapes that would work for other materials, not try to focus so much on du
plicating arundo donax. I am a bit skeptical about this. If a "normal" plas
tic or metal reed has to be shaped too much differently than existing reeds
, it would probably require an entirely different embouchure and set of mus
cles to control. The existing reed shape fits the body quite well right now
(assuming one has a "great" reed).

If I find out anything else, I will pass it on. But I suspect the plastic
shops don't deal with the UHMWPE plastics yet. And theoretically, the exis
ting tube plastics on market just don't have the tensile strength to vibrat
e at the higher frequencies needed for oboe playing--so I don't think I am
going to try that approach. I think it is clear there has been enough entre
preneurially interest that if such an approach could work, we would already
know about it.

Phil Freihofner
Oakland